I am trying to design an amplifier with a transistor model. I followed some basic tutorials online (http://microwave.eecs.utk.edu/ECE545_files/02_Lab_2.pdf) and designed a transistor model for BJT/MOSFET. I am stuck in making the amplifier work in RF frequencies. I guess either I am using a low-frequency model or improper circuitry and not sure which one of
Now, for MOSFET/BJT I fixed a bias point (for maximum transconductance in MOSFET/ fix Beta,VBE,IC,IB in BJT) and then designed the biasing circuitry and simulated the S-Parameter/AC simulation. I am getting the S21/Gain dropping to 0dB near 150 MHz. I guess this has to do with transit frequency.
I guess two mistakes - either I am using a low-frequency model or improper circuitry and not sure which.